Drafting instrument.



PATBNTED JUNE 2s, 1908.

Y W. LANGSTROTH. DRAFTING INSTRUMENT. APPLICATION'HLBD MAR. 5, 1907.

Witnesses fue NoRms P21512: co.. wAsHlNcraN, n. c.

WALTER LANGSTROTH, OF BALTIMORE, MARYLAND.

DRAFTING- INSTRUMENT.

Specification of Letters Patent.

Patented June 23, 1908.

Application filed March 5, 1907. Serial No. 360,672.

T 0 all whom it may concern.'

Be it known that I, WALTER LANGsTEoTH, a citizen of the United States ofAmerica, residing at Baltimore, State of Maryland, have invented new anduseful Improvements in Drafting Instruments, of which the following is aspecification. l

This invention relates to an improved drafting instrument for the use ofarchitectural, mechanical, topographical and other draftsmen, the objectin view being to provide a simple and effective construction of draftinginstrument adapted to afford a convenient means in perspective drawingto enable the draftsman to readily determine and lay off lines when thevanishing point of lines is at such a distance as to be beyond thelimits of the drawing board or table.

The invention is illustrated in the accome panying drawings, in Which1-Figure 1 is a top plan view of the instrument. Fig. 2 is a centrallongitudinal section thereof. Fig. 3 is a detail view of the inner endof the blade or straight edge. Fig. 4 is a detail section on the line4-4 of Fig. 1. Fig. 5 is a similar view on the line 5 5 of Fig. 2.

The instrument embodies a frame 1 com- A prising parallel end sup ortingpieces 2, a

rear cross piece 3, a plura ity of track rails 4, 5 and 6 extendingbetween said end supports, and a desired number and arrangement ofbraces 7 extending over the rear cross piece and rails and rigidlybracing and connecting them.

The rails 4, 5 and 6 are supported upon the end pieces 2 at a suitableelevation, and each is formed or provided with front and rear tracksurfaces 8, said rails being curved on arcs of different radii' andfixedly secured at their ends to the end supports 2 in any preferredmanner.

A car or carriage 9 is provided to travel upon either track, andpreferably consists of a block or plate of triangular or substantiallytriangular form with its base or widest face .forwardly disposed. Uponthe upper forward surface of the block, on opposite sides of the centerthereof, are mounted wheels or rollers 10, while upon the rear portionof the block is mounted a wheel or roller 1 1, said wheels or rollersbeing respectively grooved to engage the front and rear track surfacesof either track rail, whereby the carriage is adapted to trarlfleltransversely of the frame in an arcuate at p The rear roller 1 1 isadjustably mounted to regulate the pressure of the rollers on the railto adapt the carriage to travel steadily thereon, as well as to enablethe carriage to be applied to and removed from either rail. As shown,the roller 11 is revolubly mounted on an axle or stem 12 between a head13 thereon and a retaining ring or washer 14. Below the head 13 the axleor stem is provided with a threaded portion to project through and slidewithin a guide slot 15 in the carriage and carries a nut 16 occupying arecess 17 formed in the carriage beneath the slot .15, the said nut 16being arranged to bear against the walls of said recess by which it isheld from rotation. Above the retaining member 14 the axle or stem isprovided with a finger piece 18, whereby the stem may be adjusted tomove the nut 16 into and out of clamping engagement with the upper wallsof the recess 17 to hold the axle in adjusted'position or permitadjustment thereof. By this construction the roller 11 may be adjustedrelatively to the rollers 10 to cause said rollers to engage the tracksurfaces 8 with sufficient force to support the carriage for steadymovement and prevent play thereof, and also to permit the carriage to bedetached for the ap lication to anyone of the tracks. The rol er 11 isalso providedwitha soft rubber tire 11 to act as a cushion.

The carriage is provided on its under side with dove-tailed keeperstrips 19 forminfT a socket to receive and hold a dove-tailed block 2()attached to the inner end of a blade or straight edge 21, whereby thelatter may be attached to or removed from the carriage at will.

As before stated, the purpose of the instrument is to enable a draftsmanmaking pers ective drawings to readily determine and ay off linesespecially when the vanishing point of lines is at such a distance as tobe beyond the limits of the drawing board or table. Inpractice, aplurality of the instruments, having curved tracks varying in radii fromeach other, may be employed,

and arranged upon the drawin the blades y and as an instrument isemployed for determining each vanishing point, it will be apparent thatthe draftsman can readily arrange the instruments at the proper placeson the table convenient to the di'awing, so that by ap )lying thecarriage of each to the proper rail the blade may be connected therewithfor adjustment in the desired arc of movement. The result is arrived atby setting the instrument on the table in such a manner that the bladewill coincide with a horizontal line joining the two vanishing points.

It will be understood, of course, that the construction of the devicemay vary to a considerable extent within the purview of the invention asdefined by the appended claims, and that the rollers may be providedwith ball or other suitable anti-friction bearings to secure ease ofadjustment, if desired.

Having thus described the invention what is claimed as new, is

l. A drafting instrument of the character described, comprising a framehavinO a plurality of spaced transverse segmentLT tracks of di'l'lerentradii arranged one in reai' of the other, a carriage provided with apair of front and a single rear wheel to travel upon the tracks, an axlecarrying said rear wheel,

said axle having a sliding engagement with the carriage for adjustingthe wheel forwardly and rearwardly, means associated with the axle andengaging the carriage to retain said axle in adjusted position, and ablade connected with the carriage.

2. A drafting instrument of the character described, comprising a framehaving a plurality of spaced transverse segmental tracks of differentradii arranged one in rear of the other, a carriage provided with a pairof front and a single rear wheel to travel upon the tracks, and formedwith a slot, an axle carrying the rear wheel and on which the same isrevolubly mounted, said axle being slidably mounted in said slot foradjusting the wheel forwardly and rearwardly, adjusting` and fasteningmeans associated with the axle and engaging the carriage to retain theaxle in adjusted position, and a blade connected with the carriage.

3. A drafting instrument of the character described, comprising'a framehaving a plurality of spaced transverse segmental tracks of differentradii arranged one in rear of the other, a carriage provided with a pairof front and a single rear wheel to travel upon the tracks, and formedwith a slot and an underl ing recess communicating therewith, an ax ecarrying said rear wheel and on which the same is revolubly mounted,said axle slidably 'fitting in said slot and being provided at its upperend with a finger piece and threaded at its lower end, a head upon theaxle bearing on the upper surface of the carriage to hold the axle fromdownward movement, a nut upon the threaded end of the axle below theslot and occupying the recess, said nut being held from rotation by yoneof the side walls of the recess and bearing against the top wall of thesame to cooperate with the head, whereby the axle is clamped in adjustedposition, and a blade connected with the carriage.

In testimony whereof, I affix my signature in presence of two witnesses.

WALTER LANGSTROTH.

